🚨 Diagnostic Profile
- Vehicle/Equipment Make: GENERIC
- Technical Description: Brake Booster Motor B Phase U-V-W Circuit/Open
This code is set by the Electronic Brake Control Module (EBCM) when it detects an open circuit or phase imbalance on the ‘B’ winding (U-V-W) of the electric brake booster motor. Modern brake booster assist systems use a brushless DC motor with three-phase windings to provide hydraulic assist pressure independent of engine vacuum. The EBCM continuously monitors current feedback across all three phases (U, V, and W) to ensure the motor commutates correctly and delivers smooth, consistent brake pedal assist. When Phase B shows an open circuit, a broken winding, or a disconnected/corroded connector pin, the module loses the ability to properly drive the motor, which can result in reduced brake assist, a hard or inconsistent pedal feel, and illumination of the Brake or ABS warning indicator on the instrument cluster. This is strictly a chassis-side electrical fault isolated to the brake booster motor circuit and its connection to the EBCM.
🚨 Repair Difficulty Tier
- Difficulty Rating: Professional Only
This repair requires a bidirectional scan tool capable of communicating with the EBCM, along with a digital multimeter to perform resistance and continuity checks on the three-phase motor windings. Because the brake booster motor is a safety-critical component tied directly to hydraulic brake assist, any wiring repair, connector replacement, or motor/module swap should be performed by a trained technician with access to OEM wiring diagrams and calibration procedures.
🛠️ Resolution Steps
- Step 1: Preliminary Inspection
Visually inspect the brake booster motor connector and wiring harness for corrosion, pin damage, or chafing, particularly near the booster assembly mounting points. Check that the connector is fully seated and free of moisture intrusion, as this is a common cause of intermittent phase faults. - Step 2: Diagnostic Verification
Using a scan tool, pull freeze frame data and confirm whether C0583 is active or stored as a history code. With the connector disconnected and ignition off, use a digital multimeter to measure resistance across the U-V-W phase windings at the motor itself; compare readings to OEM specifications to identify an open or shorted winding versus a wiring harness fault. - Step 3: Resolution & Reset Process
If the harness tests faulty, repair or replace the damaged wiring and connector, ensuring proper pin tension and waterproofing. If the motor windings themselves test out of specification, replace the brake booster motor/pump assembly as a unit. After repair, clear the stored code with a scan tool, cycle the ignition, and perform any required EBCM relearn or booster calibration procedure specified by the manufacturer.
📦 Parts, Labor, and Budget Estimates
- Required Components/Software: Brake booster motor/pump assembly (if faulty), wiring harness repair kit or connector, bidirectional scan tool with EBCM calibration capability
- Average Component Price: $180 – $450 USD
- Estimated Labor Hours: 1.5 – 3.0 hours
- Total Estimated Budget: $300 – $650 USD